1. Field of the Invention
The present invention relates generally to electromagnetic fluid flow meters and, more particularly, to a flow meter which requires no structure protruding into the fluid flow.
2. Description of the Prior Art
In the development of electromagnetic fluid flow meters, a number of approaches have been taken, all of which are dependent upon the fact that when a pair of electrical contacts are in contact with a flowing fluid and there is a component of an electromagnetic field perpendicular to that flowing fluid, an electrical potential will be generated between the electrodes which is proportional to the velocity of the fluid past the electrodes and to the strength of the magnetic field. The most common configuration for a device for utilizing this physical principle is a "rodmeter" as evidenced by the Snyder et al U.S. Pat. No. 2,969,673 and Springston, Jr. U.S. Pat. No. 3,677,082.
In devices of this type, the electromagnetic field is generated by an electromagnet located in a rod or wand submerged in the field flow itself which, in the case of Snyder and Springston, Jr., is a structure which is suspended below the hull of a marine vessel. The electrodes are mounted on the sides of the rod and are in contact with the water flowing past it. While these devices function adequately, there are problems with the rod structure itself extending beyond the hull of the vessel, a feature particularly undersirable for small sailing vessels.
Another approach which has been taken is to mount the electrodes practically flush with the surface past which the fluid flows and provide a similar electromagnetic field between the electrodes. One prior art approach utilizing this concept is shown in the Kenyon U.S. Pat. No. 3,119,960. In the Kenyon technique, the electromagnetic field is provided by a relatively conventional electromagnet construction which requires special mounting techniques as the overall structure is relatively large.
While the prior art mounting flow meter constructions are adequate for some purposes, the elaborate mounting schemes normally required make them unsuitable for use in vessels such as pleasure craft which require relatively simple installation and maintenance. The flow meter constructure of the present invention provides a long-felt need for an electromagnetic flow meter for such applications.